Got Modnation Racers for the Vita today, am impressed enough to plan on getting it for the PS3.

It's your usual kart racing vibe, with this twist: pretty much all of it is open to modification. You can create tour own character, car and even make your own track, and then share those with other players online. You can leave them open to modification by others or close them off to stranger-fiddling.

As with most racing games, you can have one-off races or enter a campaign; as you win races you unlock more things to use.